Add PKCS#8 ECPrivateKey export/import functions.

crypto/ec_private_key.cc

Index: crypto/ec_private_key.cc
diff --git a/crypto/ec_private_key.cc b/crypto/ec_private_key.cc
index 5e8d0549a85f00f60fa7f699898af354bfd6df49..300d498368dd5857f4b6735eec1245176c4c4e48 100644
--- a/crypto/ec_private_key.cc
+++ b/crypto/ec_private_key.cc
@@ -90,6 +90,30 @@ ECPrivateKey* ECPrivateKey::Create() {
 }
 
 // static
+std::unique_ptr<ECPrivateKey> ECPrivateKey::CreateFromPrivateKeyInfo(
+    const std::vector<uint8_t>& input) {
+  OpenSSLErrStackTracer err_tracer(FROM_HERE);
+
+  CBS cbs;
+  CBS_init(&cbs, input.data(), input.size());
+  ScopedEVP_PKEY pkey(EVP_parse_private_key(&cbs));
+  if (!pkey || CBS_len(&cbs) != 0)
+    return nullptr;
+
+  // Check this is a P-256 key.
+  EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(pkey.get());
+  if (!ec_key ||
+      EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) !=
+          NID_X9_62_prime256v1) {

[Ryan Sleevi, 2016/05/02 23:26:56]

Why? We don't enforce this elsewhere, AFAICT. It's implicit in
ExportPublicKeyRaw, but my point here is that this isn't documented in the
header as part of the API contract, nor consistently enforced. I have no
objections to enforcing this consistently, and to clearly documenting that
contract - but this feels asymmetric and underspecified in the present form.

[davidben, 2016/06/01 17:19:39]

I think it's a little poor to have parsing be able to create keys that we would
never parse. But, fair enough, if we're to limit it to P-256, it should be done
uniformly and with tests. Took that bit out. We can sort it out separately.

[davidben, 2016/06/01 17:19:58]

s/would never parse/would never create/

+    return nullptr;
+  }
+
+  std::unique_ptr<ECPrivateKey> result(new ECPrivateKey);
+  result->key_ = pkey.release();
+  return result;
+}
+
+// static
 ECPrivateKey* ECPrivateKey::CreateFromEncryptedPrivateKeyInfo(
     const std::string& password,
     const std::vector<uint8_t>& encrypted_private_key_info,
@@ -137,9 +161,24 @@ ECPrivateKey* ECPrivateKey::CreateFromEncryptedPrivateKeyInfo(
   return result.release();
 }
 
-bool ECPrivateKey::ExportEncryptedPrivateKey(const std::string& password,
-                                             int iterations,
-                                             std::vector<uint8_t>* output) {
+bool ECPrivateKey::ExportPrivateKey(std::vector<uint8_t>* output) const {
+  OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  uint8_t* der;
+  size_t der_len;
+  AutoCBB cbb;
+  if (!CBB_init(cbb.get(), 0) || !EVP_marshal_private_key(cbb.get(), key_) ||
+      !CBB_finish(cbb.get(), &der, &der_len)) {
+    return false;
+  }
+  output->assign(der, der + der_len);
+  OPENSSL_free(der);
+  return true;
+}
+
+bool ECPrivateKey::ExportEncryptedPrivateKey(
+    const std::string& password,
+    int iterations,
+    std::vector<uint8_t>* output) const {
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   // Convert into a PKCS#8 object.
   ScopedPKCS8_PRIV_KEY_INFO pkcs8(EVP_PKEY2PKCS8(key_));
@@ -168,7 +207,7 @@ bool ECPrivateKey::ExportEncryptedPrivateKey(const std::string& password,
                           output);
 }
 
-bool ECPrivateKey::ExportPublicKey(std::vector<uint8_t>* output) {
+bool ECPrivateKey::ExportPublicKey(std::vector<uint8_t>* output) const {
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
   uint8_t *der;
   size_t der_len;
@@ -183,7 +222,7 @@ bool ECPrivateKey::ExportPublicKey(std::vector<uint8_t>* output) {
   return true;
 }
 
-bool ECPrivateKey::ExportRawPublicKey(std::string* output) {
+bool ECPrivateKey::ExportRawPublicKey(std::string* output) const {
   OpenSSLErrStackTracer err_tracer(FROM_HERE);
 
   // Export the x and y field elements as 32-byte, big-endian numbers. (This is
@@ -205,22 +244,6 @@ bool ECPrivateKey::ExportRawPublicKey(std::string* output) {
   return true;
 }
 
-bool ECPrivateKey::ExportValueForTesting(std::vector<uint8_t>* output) {
-  OpenSSLErrStackTracer err_tracer(FROM_HERE);
-  EC_KEY* ec_key = EVP_PKEY_get0_EC_KEY(key_);
-  uint8_t *der;
-  size_t der_len;
-  AutoCBB cbb;
-  if (!CBB_init(cbb.get(), 0) ||
-      !EC_KEY_marshal_private_key(cbb.get(), ec_key, 0 /* enc_flags */) ||
-      !CBB_finish(cbb.get(), &der, &der_len)) {
-    return false;
-  }
-  output->assign(der, der + der_len);
-  OPENSSL_free(der);
-  return true;
-}
-
 ECPrivateKey::ECPrivateKey() : key_(NULL) {}
 
 }  // namespace crypto